Que as the start of a new thought that’s consequential to the last one
“Vamos ya, que tengo hambre” → “Let’s go now, (because/since/it’s that) I’m hungry
“Cómprate esa falda que te queda cabrona” → “Buy that skirt (because/since/it’s that) it fits/turned out so good on you”
“Prueba el pan que está buenísimo” → “try the bread (because/since/it’s that) it’s so good”
In English we would probably omit because/since/it’s that in these sentences and just start a separate thought with a pause “Buy that skirt, it looks so good on you.” In Spanish we can also do that, but it’s very common to use que to connect your thoughts in this way.
By contrast, the use of Que we’re probably most familiar with is:
Que as that/which
“Dijo que te quiere ver.” → “He/she said that he wants to see you."
"Hay muchos lugares aqui que te van a gustar.” → “There are a lot of places here that/which you’re going to like.”
In English we can omit “that” in these sentences - in Spanish we cannot. We need que.